Liquid heating in interaction region of microwave generator

Abstract

A microwave heater (22) which uses electromagnetic radiation for heating liquid flowing from a liquid source to a liquid receiver. The microwave heater (22) includes a microwave generator having an interaction region (28) within which the electromagnetic radiation is generated. At least a portion of a conduit (30) which has an inlet (32) connected to the liquid source and an outlet (34) connected to the liquid receiver is deployed within the interaction region (28). The liquid flows through the conduit (30) acting as a dielectric load of the microwave generator so as to be heated by the electromagnetic radiation.

What is claimed is: 
     
       1. A microwave heater which uses electromagnetic radiation for heating liquid flowing from a liquid source to a liquid receiver, the microwave heater comprising a microwave generator having: (a) a microwave generating tube containing at least one interaction region within which the electromagnetic radiation is generated; and   (b) at least one conduit having an inlet connected to the liquid source and an outlet connected to the liquid receiver, a portion of said at least one conduit being deployed within at least one of said at least one interaction region, the liquid flowing through said portion acting as a dielectric load of said microwave generator so as to be heated by the electromagnetic radiation.   
     
     
       2. A microwave heater as in claim 1, wherein said inlet is positioned lower than said outlet such that, when the microwave heater is in use, convective effects tend to generate a flow of the liquid from the liquid source to the liquid receiver. 
     
     
       3. A microwave heater as in claim 1, wherein said at least one interaction region is substantially cylindrical and has an axis, and wherein a beam of electrons passes through said interaction region substantially parallel to said axis, said at least one conduit forming a substantially peripheral flow path within said interaction region. 
     
     
       4. A microwave heater as in claim 3, wherein said substantially peripheral flow path is tapered along said axis so as to synchronize the phase velocity of the electromagnetic radiation with the velocity of said beam of electrons along said interaction region. 
     
     
       5. A microwave heater as in claim 3, wherein said interaction region includes an axially periodic structure. 
     
     
       6. A microwave heater as in claim 5, wherein said axially periodic structure is metallic. 
     
     
       7. A microwave heater as in claim 6, wherein said axially periodic structure is helical. 
     
     
       8. A microwave heater as in claim 3, further comprising means for applying an axial magnetic field through at least part of said interaction region parallel to said axis. 
     
     
       9. A microwave heater as in claim 8, wherein said axial magnetic field is fixed so as to define the frequency of the electromagnetic radiation generated. 
     
     
       10. A microwave heater as in claim 3, further comprising means for applying a magnetic field through at least part of said interaction region substantially perpendicular to said axis. 
     
     
       11. A microwave heater as in claim 3, wherein said substantially peripheral flow path defines an axial void, the microwave heater further comprising a plurality of elongated conductors arranged within said axial void, each of said elongated conductors being substantially parallel to said axis. 
     
     
       12. A microwave heater as in claim 3, wherein said substantially peripheral flow path has an inner surface, the microwave heater further comprising a plurality of annular conductors spaced along said inner surface, each of said annular conductors being perpendicular to said axis. 
     
     
       13. A microwave heater as in claim 1, wherein said at least one conduit is formed from glass protected by a fine metallic coating. 
     
     
       14. A microwave heater as in claim 1, wherein said microwave generator is a Cerenkov maser which uses the liquid as a functional dielectric. 
     
     
       15. A microwave heater as in claim 1, wherein said microwave generator is a cyclotron resonance maser. 
     
     
       16. A microwave heater as in claim 1, wherein said microwave generator is a free electron maser. 
     
     
       17. A microwave heater as in claim 1, wherein said microwave generator is a coaxial-type magnetron having a plurality of circumferentially spaced cavities, and wherein a plurality of said conduits substantially fill said plurality of circumferentially spaced cavities. 
     
     
       18. A method of heating a liquid comprising the step of passing the liquid through a conduit, at least part of the conduit being deployed within an interaction region of a microwave generating tube within which microwave radiation is being generated. 
     
     
       19. The method of claim 18, wherein the microwave generating tube is a magnetron tube.